Method and device for transferring a product in a packaging machine

ABSTRACT

In a method for transferring a product in a packaging machine, the product is engaged from behind by a pushing element which is mounted on and driven by a first circulating continuous conveyor and moved from a transfer station along a sliding surface for transfer to an ongoing conveyor device. While being moved, the product is guided between the pushing element and a forward limiting element which is mounted on a second circulating continuous conveyor. To ensure a precise, rapid transfer, the forward limiting element is returned to the transfer station after the product has been moved by the carrying run of its second continuous conveyor and is used as the pushing element for the next product to be moved. The pushing element is guided back to the transfer station in the opposite direction to that in which the product is conveyed by means of its first continuous conveyor and is used as the limiting element for the next product to be moved.

BACKGROUND OF THE INVENTION

The invention concerns a transfer device in a packaging machine inaccordance with the independent claim.

In a packaging machine, the products and the packages, which can be e.g.folding boxes, must pass several stations either individually or as aunit with the product accommodated in the package. In the sense of theapplication, the term product means each individual product and also astack of individual products, e.g. blister strips handled as a unit.

Endless chain or conveyor belts are often used as a transport devicewithin the packaging machine, wherein the packages and/or the productsare supplied on the upper run. The following discussion is based, by wayof example, on the transfer of a blister stack, consisting of severalblister strips disposed on top of each other on a product conveyor belt.

The individual blisters are disposed on top of each other in a stackingstation to form a blister stack and are then transferred to the productconveyor belt via a transfer device (EP 0 876 278 B1). The transferdevice comprises a sliding surface, one end of which accommodates, in atransfer station, the blister stack which is to be transferred. At aseparation above the sliding surface, an endless conveyor is providedwhich circulates in a vertical plane and carries several projectingfingers circulating with the endless conveyor. To displace the blisterstack across the sliding surface, a finger can engage behind the blisterstack and carry it while moving along the lower run of the endlessconveyor. At the end of the sliding surface, the blister stack is pushedonto the product conveyor belt and is disposed, in particular, in acompartment formed thereon, thereby terminating the transfer.

This type of displacement of the blister stack over the sliding surfacehas various disadvantages. On the one hand, the finger must bepositioned very precisely relative to the blister stack to avoideccentric introduction of the pushing force and thereby jamming ordisalignment of the blister stack. Since the width of the blister stacksto be moved by the transfer device varies depending on the size of therespective blister strips, the position of the fingers must always bere-oriented when the product is changed, which is demanding andlaborious. Moreover, there is the risk that the blister stacks arereleased from the finger during sudden stoppage of the transfer devicedue to their inertial force to continue to slide over the slidingsurface through a short stretch, without guidance, wherein they usuallylose their predetermined orientation and must be removed from thepackaging machine by an operator to guarantee proper operation when thetransfer device is restarted.

In CH 410 759, which discloses a means of this type, a stack of productsis inserted into a continuous transport channel by means of amulti-component push arm which is mounted to a first circulating endlessconveyor. The transport channel is associated with a second circulatingendless conveyor which carries transport straps for displacing theproduct stack along the transport channel after the push arm has pushedthe stack into the transport channel. The speed and orientation of thepush arm and the transport straps are adjusted such that the productstack is loaded on its rear side by the push arm at the end of theeffective transport path of the first endless conveyor of the push arm,while its front side abuts the advancing transport strap such that amomentary state is thereby achieved in which the product stack isreceived between two elements.

Such a transfer also involves the above-mentioned drawbacks since theproduct stack is only in contact with the push arm along nearly theentire displacement path.

It is the underlying purpose of the invention to produce a method and adevice for transferring a product in a packaging machine whicheliminates the above-mentioned disadvantages to transfer the productwith high precision.

SUMMARY OF THE INVENTION

This object is achieved in accordance with the invention with the devicehaving the characterizing features of the independent claim.

In accordance with the invention, the pushing motion of the product orof the blister stack is achieved in a conventional manner via thepushing element which engages behind the product, which may be one ormore adjacent fingers or also a push plate. During its entiredisplacement, the product is guided between the pushing element and theadvancing limiting element, preferably with tight fit. The advancinglimiting element which can also be one or more adjacent fingers or alimiting plate, prevents the product from being released from thepushing element during sudden stoppage of the transfer device tocontinue to slide in an uncontrolled fashion. Moreover, the limitingelement prevents, in cooperation with the pushing element, inclinedpositioning of the product, since the product is precisely positionedbetween the pushing element and the limiting element. The separationbetween the pushing element and the limiting element can be selectedsuch that the product is clamped between these elements with slightpretension. However, the separation between the pushing element and thelimiting element preferably corresponds exactly to the width of theproduct such that it is held between the two elements without anytension.

To achieve high efficiency with the transfer device, a new product or anew blister stack should be introduced during times at which theprevious product is still being displaced. To be able to receive theprovided product quickly and securely between the pushing element andthe limiting element, the invention provides that the advancing limitingelement is returned to the transfer station, after termination ofdisplacement of the product, by means of its first endless conveyor and,in particular, via its upper run to serve as pushing element for thenext product to be displaced, which is already disposed in the transferstation, by abutting the rear side thereof. The pushing element used forthe previous product is returned to the transfer station against theproduct transport direction by means of its second endless conveyor and,in particular, via its lower run and abuts the front side of theprovided product at that location such that it serves as a limitingelement for same during the displacement process. In this manner, thefingers of the one endless conveyor and the fingers of the other endlessconveyor are alternately used as pushing element and as limitingelement, respectively.

It has been demonstrated that an eccentric disposition of the pushingelement relative to the product, i.e. eccentric introduction of thepushing force, does not disalign the product due to the limitingelement, since the torque resulting from such eccentricity isaccommodated for by the limiting element in cooperation with the pushingelement. In this fashion, demanding centering of the pushing elementrelative to the product is not required.

When the format is changed, the separation between the pushing elementand the limiting element must merely be adjusted to the width of the newproduct. Towards this end, the pushing element and the limiting elementare advantageously mounted to different endless conveyors which can beadjusted relative to each other. The two endless conveyors arepreferably driven independently of each other, wherein the drive motionsare synchronized during the entire displacement process of the productto maintain the predetermined separation between the pushing element andthe limiting element.

The above-mentioned object is achieved in a device having thecharacterizing features of the independent claim. The limiting elementwhich advances the product is mounted to the second circulating endlessconveyor and is driven thereby, wherein the product is guided betweenthe pushing element and the limiting element, preferably with closetolerance. The pushing element and the limiting element are therebymounted to different endless conveyors, each of which is preferablyprovided with its own drive device such that, after termination ofdisplacement of a product in the above-mentioned manner, differentreturn motions for the elements can be provided.

The endless conveyors are preferably disposed above the sliding surfaceand each circulate parallel to another in a vertical plane.

In accordance with the invention, each endless conveyor can be driven intwo directions as a result of which, after termination of thedisplacement process of a product, the advancing limiting element can bereturned, in particular via the upper run of its endless conveyor, tothe transfer station while the pushing element is returned to thetransfer station against the product transport direction, in particular,via the lower run of its endless conveyor. For the next product to bedisplaced, the elements thereby swap function, i.e. the previouslimiting element becomes the pushing element while the previous pushingelement assumes the function of the limiting element.

Further details and features of the invention can be extracted from thefollowing description of embodiments with reference to the encloseddrawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective lower view of the endless conveyor;

FIG. 2 shows the schematic representation of the inventive transferdevice in a starting position;

FIG. 3 shows the transfer station according to FIG. 2 at the end of thedisplacement process;

FIG. 4 shows the transfer station in accordance with FIGS. 2 and 3during return motion of the fingers; and

FIG. 5 shows the transfer station in a starting position for thesubsequent product to be displaced.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2 shows a schematic side view of an inventive transfer device 10 ina packaging machine. It shows, in a conventional fashion which is notfurther explained herein, a product in the form of a blister stack 15 ina transfer station 18 which comprises an elevating platform 16. Theelevating platform 16 is joined at the same level by a sliding surface17 which is positioned at its opposite end close to the upper run 21 aof a continuous transport device 21 which is e.g. the product transportchain of a packaging machine. The blister stack 15 is to be displacedfrom the elevating platform 16, via the sliding surface 17, to thecontinuous transport device 21 and be pushed onto its upper run 21 a.

To perform the displacement motion, two circulating endless conveyors11, 12 are provided at a separation above the sliding surface 17 whichcirculate parallel and next to another in a vertical plane (FIG. 1).Each of the two endless conveyors 11, 12 has its own drive device 19, 20and the endless conveyors 11, 12 can be driven in two directions,independent of one another. The first endless conveyor 11 is provided,via a mounting section 13 a, with the base of a U-shaped finger fork 13which opens towards the bottom and circulates with the first endlessconveyor 11 and which extends sidewardly to above the parallel secondendless conveyor 12. A similar U-shaped second finger fork 14 is mountedto the second endless conveyor 12 via a mounting section 14 a, whichextends sidewardly up to the region of the first endless conveyor 11 andis oriented towards the first finger fork 13 in the direction of motionof the endless conveyors 11 and 12.

FIG. 2 shows the original position of a transfer or displacement processfor the blister stack 15 which is to be displaced to the continuoustransport device 21 via the sliding surface 17 in the direction B. Thefirst finger fork 13 abuts the rear side of the blister stack 15, viewedin the direction of motion B, and serves as pushing element. The secondfinger fork 14 is mounted to the opposite front side of the blisterstack 15, viewed in the direction of motion B, such that the blisterstack 15 is disposed between the two finger forks 13 and 14 with tightfit and little play.

At the start of the transfer process, the two endless conveyors 11 and12 and therefore the finger forks 13 and 14 are synchronously driven inthe same direction B thereby exerting a pushing force onto the blisterstack 15 in the direction of B via the finger fork 13 acting as pushingelement, the pushing force displacing the blister stack 15 from theelevating platform 16 onto and across the sliding surface 17. Theadvancing finger fork 14 which acts as limiting element thereby preventsthe blister stack 15 from slanting or being released from the trailingfinger fork 13.

The synchronized motion of the two endless conveyors 11 and 12 continuesuntil the blister stack 15 has been pushed onto the upper run 21 a ofthe continuous transport device 21 such that it is accepted thereby (seeFIG. 3). While the blister stack 15 is displaced across the slidingsurface 17, the next blister stack 15′ is stacked onto the elevatingplatform 16.

From the transfer position to the continuous transport device 21 (seeFIG. 3) the finger forks 13 and 14 must be returned to the transferstation 18. This is effected through different motions of the endlessconveyors 11 and 12. The advancing finger fork 14 is returned via theupper run of the second endless conveyor 12 (see FIG. 4) and then abutsthe rear side of the new blister stack 15′ disposed on the elevatingplatform 16 (see FIG. 5). In this fashion, the finger fork 14 which isused as the upstream limiting element for the blister stack 15, is usedas the trailing pushing element for the subsequent blister stack 15′.

The finger fork 13 which serves as pushing element for the blister stack15 is returned to the transfer station 18 by reversing the direction ofmotion of the first endless conveyor 11 (see FIG. 4) to abut the frontside of the blister stack 15′ which is prepared for displacement. Thefinger fork 13 used up to now as pushing element for the blister stack15, now serves as upstream limiting element for the subsequent blisterstack 15′. FIG. 5 shows the position of the finger forks 13 and 14 afterreturn to the transfer station 18. The constellation shown thereincorresponds substantially to the starting position of FIG. 2, with thetwo finger forks 13 and 14 simply being exchanged. From the positionshown in FIG. 5, the blister stack 15′ is transferred to the continuoustransport device 21 in the manner described, whereupon the two fingerforks 13 and 14 are returned while thereby interchanging theirfunctions.

We claim:
 1. A transfer device in a packaging machine for displacing aproduct from a transfer station along a sliding surface to a continuoustransport device, the transfer device comprising: a first circulatingendless conveyor having an first upper run and a first lower run, saidfirst endless conveyor circulating in a substantially vertical planeabove the sliding surface; a first drive mechanism cooperating with saidfirst endless conveyor to drive said first endless conveyor in twodirections; a second circulating endless conveyor having a second upperrun and a second lower run, said second endless conveyor circulating ina substantially vertical plane, above the sliding surface and parallelto said first endless conveyor; a second drive mechanism cooperatingwith said second endless conveyor to drive said second endless conveyorin two directions; a first U-shaped finger fork mounted to said firstcirculating endless conveyor, said first fork having a first fork endfacing away from said first endless conveyor which is open; and a secondU-shaped finger fork mounted to said second circulating endlessconveyor, said second fork having a second fork end facing away fromsaid second endless conveyor which is open, wherein, in a first transferprocess, the product is disposed between said first fork and said secondfork, said first fork pushing the product and said second fork disposedupstream of the product to limit forward motion of the product, whereinafter transport of the product to the transport device, the first forkis returned to the transfer station along said first lower run, againsta transport direction of the product, to assume a position upstream of anext product to be transferred and said second fork is returned to thetransfer station along said second upper run to assume a pushinglocation behind said next product to be transferred.
 2. The transferdevice of claim 1, wherein said first and said seond finger forks areoriented substantially vertically during displacement of the product. 3.The transfer device of claim 1, wherein the product can be receivedbetween said first and second finger forks with tight fit during itsentire displacement motion.
 4. The transfer device of claim 1, wherein aseparation between said first and said second finger forks is selectedto hold the product between said first and second forks with slightpre-tensioning during its entire displacement motion.
 5. The transferdevice of claim 1, wherein said first and said second drive mechanismscan be synchronized to maintain a predetermined separation between saidfirst and said second finger forks during transport of the product. 6.The transfer device of claim 1, wherein said first and said secondendless conveyors can be adjusted relative to each other.